I played DnD 3.5 while in the military and due to a shortage of DMs, was constantly flooded by players. Some of my games would include up to 10 or 11. I discovered quickly that balancing for this in 3.5 was neigh impossible: either the enemies would die before they could react, or the players were so over matched they could not hit them at all.

I tried horde style fights, big boss fights, etc, and generally it resulted in either massacre of the opponents, or TPK with nothing really being a satisfactory fight. I even would double or triple the HP of enemies to make it work.

Most game systems have a breaking point. How do you tweak systems to be accommodating for groups that far above the recommended limit?

Note: Simply telling people they can't join, or running two campaigns is simply not an option given the situation.

4 Answers
4

Having run stable 13-player groups (with everyone showing up every week, no less) in several systems, a large group has 4 issues:

1) face time for every player
2) Synergy of group size.
3) Appropriate challenges for the group as a whole
4) GM communications

1 Face Time

Now, my big group for D&D3.X was 9 players, not 13, but finding challenges (especially given the average level was 10th) was minor compared to just making certain every player got some face time twice or more every session. That was handled best by simply having NPC's target different PC's for their interactions; in other words, not leaving it to the players to decide who interacts with a given NPC.

2 Synergy

The synergy effect comes from overlapping skills and the help rules. Which said, the help rules in 3.x are pretty weak, but they do add up. Further, with large groups in 3.X, you'll tend to get more over-the-top combat potential due to players having similar roles.

3 Challenges

The challenge issue is an evolution of the synergy issue. Remember - not every monster is intended to be the "ideal party" challenge; many are really balanced for an ideal party but are taken out mostly by one member of said party, often the wizard or the fighter. (Keeping in mind: ideal party is 1 fighter, 1 wizard or sorcerer, 1 cleric, and 1 rogue.) Most are fighter based - and my experience is that large parties tend to be heavy on fighters and wizards, light on rogues and clerics, and having few of anything else. So, often, combats will depend on how competent the targeted players are.

Further, fights with a few large monsters tend to become very one-sided when the first big-bad goes down, as those resources fighting it get diverted to the others. That's normal; it's just more obvious in larger groups.

Some specific cases to remember:

Undead: aimed at clerics, especially the incorporeal ones. Balance the encounter based upon the party being the level of your clerics, and sized at 4x your number of clerics. Simpler undead, like skeletons, who present no conversion issues, can be used to protect the higher level undead from turning, but also can be taken out by fighters and combat wizards easily.

Incorporeal anything: clerics and wizards - the fighters are close to useless. For large groups, always give the fighters something to face that's corporeal.

potent monsters: many monsters are highly potent - some surprisingly so - such as Illithids and Beholders. Don't add more to balance them; add subservient fighters instead. Beholders, for example, should usually be solitary - to buff it up, add enslaved kobolds or orcs, or a couple lucky rounds will be a snowball effect.

4 Communication with the GM

The solutions vary by group, but mostly break down to turn taking or collating. Usually in some combination. Some additional options

4a Collating Actions

By collating, this means a small number of players talk to the GM, but tell the GM what their and several other players' characters are doing; it is a variation on the single "caller" of AD&D rules fame.

The classic solution was to run the game as a minis wargame, with ONE player collecting/collating everyone's actions. It works, but it can be unsatisfying. It is, however, how E. Gary Gygax ran parties of up to 20 players.

4b Turn Taking

Simply make certain that turn taking isn't just in combat. When it comes time to get actions, go around and pointedly ask each player for what they're doing. Much above 5 players, the traditional popcorning of actions no longer is viable, as the noise it generates becomes considerable, and too much gets missed.

4c Harlequins

A Harlequin is a player who plays only NPCs. They don't narrate, don't resolve game rules, and don't get special authority. They are a real challenge for some groups, but in larger groups can be spectacularly successful at reducing the GM overload.

This is especially true in certain types of play. For example, in one large (13 player, 25 PC), I had a 14th player who couldn't show regularly. When he did, he got to play NPC's. If he was negotiating with the players, I'd give him a list of what his allowed resources were, and turn him loose with the away team sent to deal with him. Meanwhile, I'd do the GM-needed interactions to solve the overlapping mechanical problem of the week. And when done, he'd note down the final resolved issue.

Further, Harlequins allow the GM to have really GOOD dialogue from multiple NPC's.

The drawbacks are that many can't make the distinction between assistant GM and Harlequin. It can be set onto a continuum, where certain situations the harlequin is allowed to call for certain rolls, and that works, but once they start calling for rolls for anything other than affecting the character they play, they're really into being assistant GM's.

4d Assistant GM's

The problem with an assistant GM is trust. You HAVE to trust them not to muck up your adventure. The benefit is that you don't have to run the whole group all the time, and if the party splits, you take one part and they take the other.

Assistant GM's are best made from harlequins, not experienced GM's. Start letting the harlequin players call for rolls, and slowly build them up to being part of the resolution in general.

It's very important not to have the assistant GM's contradict your calls, but likewise, if it's not a rules issue, if they make a call, back it up.

5 Problem Players

Some types of players tend to be problems in certain groups... the classics being Rules Lawyers, Attention Hounds, and Shy Guys.

5A The Rules Lawyer

Co-opting the rules lawyer to assistant GM is great in minis-mode, not so good in story mode. Leave him/her as a normal player, but ask them for advice on rules issues. Don't make them officially assistant GM's.

5b The Attention Hound

The Attention Hound really works well as a harlequin. It puts him in the center of things, but also keeps him from eating your time as GM.

5c The Shy Guy

This is the guy who shows up, but doesn't really speak up. The kind who act only when asked, "What's your character doing?"

The shy guy, in a small group, can be coaxed by the GM into playing. In a large group, they often fall by the wayside. The trick is often to have another player prompt them; in some cases, having them be the caller for a small portion of the group can break them out of their hesitance.

what is a "caller"? I've never heard the term before
–
TetraFeb 1 '12 at 23:46

The caller was the player who acted as the interface between GM and players. The players all told the caller their actions, and the caller then told the GM. I've seen it used only rarely.
–
aramisFeb 2 '12 at 0:52

1

These are some really great tips for large group roleplaying, or even just multi-GMing a game even when the player count is low.
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ZibbobzAug 20 '14 at 18:06

I've had open fate games that fall into the "wow big group showed up tonight.. OMG there are like 3 more new people standing quietly behind me I didn't see till someone mentioned them!" end of the spectrum at a FLGS that range from a handful of regulars to "yea we are definitely going to move some of the tables!"

In a structured game like 3.5/PF (no experience with 4.0 myself), your in for a hell of a time trying combat with a group that large though & it's tough to let the group split themselves towards different legs of a common goal. With a fate based system like Spirit of the Century or Dresden files RPG where the walls constraining them run away screaming from the shared rules light nature of things in a fun way it's no big deal. when you plan for 3-4 people and like a dozen show up, you can wing it & go from dealing with something minor to some epic big-bad letting everyone scatter into smaller groups finding things like a boat/plane/etc as needed & investigating the few details you were able to think of in the last 5 minutes while letting them help you do so with things like mining what/how they tell you they want to find out first. so you guys think you are giing to need a boat?... how are you going to get it? oh look.. the social butterflies split off on their own across town while the investigator types went digging for clues on their own & roped the techie in with them to do some hacking "in case" (Wooo they just gave you an encounter!)

Ok... the group figured out they need to get into [place], lets say it's a high security office building for simplicity. As a GM you can describe a big high security office building with a guard in the lobby. Let the group flesh out the details for you & play to their skills in the process. "what kind of security do they have?" can bounces back at the group with something like "it looks pretty normal on the surface... but their earlier research indicated that it's probably anything but if you peel back the curtain even a smidge... how are you going to find out?" When the sneaky sneaky guy decides he wants to find weaknesses ion the camera patterns in the lobby & [social butterfly] offers to help, you now have two players split off working together on a tiny fraction of the whole (which may or may not be getting rolled out off the cuff!) everyone works together towards a common goal and there are a couple minor encounters here & there against a couple people that split off to accomplish saomething

Sneakysneaky guys manage to disable the main security so the group can get into stop the bigbigbigbad from doing [whatever]use the environment against them too. Spiffy, they managed to sneak in partway (awesome for you) toss in a random guard just being friendly or some kind of wards/alarmy obstacles that cause a frackish in the middle of the enemy stronghold.... suddenly it's not a 12 on a couple just melting powerful things in one round with focused fire, it's 12players on 15-20+ mooks where fight focused characters get to mow down mooks like they were pro football players up against 6year olds in a game of smear the queer while the less combat oriented folks get to work together to make a tend in the flood & provide a meaningful impacvt on helping out in the combat beyond "Uhh.. oh it's my turn? I'm going to hit it again... I guess" like with d&d type tactical things where stuff designed to challenge the combat brutes will effortlessly mop the floor with the noncombat types. use this time to figure out what's going to be coming up when they finish.

The rules are easy to explain through "you have this many skillpoints & here is a cheatsheet listing skills & such, what do you want to try and do, I'll explain how to go about trying it & we will figre out how things go down as a group" & characters can be made during play for the most part (wizards & kind of the exception because magic has some extra rules that can be rough to explain off the cuff to someone who knows nothing about the game)

Fate is a beautiful system for letting the GM wing it without a clue where the hell they are going while making it look like they know exactly where they are going & juggling a crazy amount of details. how are the cameras laid out is as simple as giving an aspect like "there are lots of cameras laid out in a relatively secure pattern/sweep". Since it's not a tactical thing (it's zones of things like "lobby, hallway, elevator shaft, research labs, safe room, etc"), the cameras are anywhere that you decide their presence can make things interesting requiring rolls is the same way, require one when it can make things interesting, no need to slow things down with rolling every minute detail.
If you really do get stuck post bigbad, you can always mine your players by throwing out useless crumbs of info & seeing where they go with them while you construct enough shoestrings to get through to the end of the session, or you can just do some city creation type stuff (it's a group thing with some rules & fun once people know the system a bit)

edit: with fate based systems you also have bits that go from d&d style letting folks split off on their own & spend a short time doing their part of the whole. Things like "Your not there shutup", change to "Yea that's a good idea" or "well... maybe not like that, probably more..." since they can help fill in details and guide things . Even better if they jelp you guide things in interesting ways you can mine for ideas while you are filling in details behind their back. People will often try to make suggestions that interest the or that they think would be interesting for the group even with structured d&d type games.

This happens several times a year for me. We plan on people being absent, someone else has a friend they want to bring to fill in, and more people show up - the group goes from 5-6 to 8 or more. Fortunately, i require a party leader and spell out what i expect. The party leader helps me to ensure each person gets some time to shine. I rarely write any encounters for characters - i write them for roles and let the party decide who fills them when possible. The burden shifts and allows me to run a better encounter than trying to deal with a 'foiled plan'. For strict game balance, again i put the onus more on the party themselves. A good party will work together and a great party leader will help make them super effective. I never try and let them over-represent anything but warrior archetypes. These are typically warriors and _. Its the _ that i try and make a role for - not the character themselves. Also, knowledge is a huge part of my games (lores, sciences, languages, etc.) so many times each character has a unique bit of knowledge they can draw on at a critical moment. Lastly, and its been mentioned, have NPC's or effects target specific PC's. But i'll end by emphasizing its better if you have help from the party itself to assist in this - a party leader will delegate tasks ank help make sure everyone gets a chance, leaving GM's to focus more on making the encounter seamless and fun. This also has the effect of making the party feel more like they are in control, rather than you forcing the issue.